Problem-solving via search

Description

Problem-solving via search is a fundamental concept in Artificial Intelligence where an agent attempts to find a sequence of actions that leads from an initial state to a goal state. This is achieved by exploring a search space, typically represented as a tree or graph, where each node represents a state and edges represent actions. AI uses various search algorithms—either uninformed (blind) or informed (heuristic)—to efficiently find solutions.

Examples (Code)

Below is a simple example


from collections import deque

# Graph represented as an adjacency list
graph = {
    'A': ['B', 'C'],
    'B': ['D', 'E'],
    'C': ['F'],
    'D': [],
    'E': ['F'],
    'F': []
}

def bfs(start, goal):
    visited = set()
    queue = deque([[start]])

    while queue:
        path = queue.popleft()
        node = path[-1]

        if node == goal:
            return path

        if node not in visited:
            visited.add(node)
            for neighbor in graph.get(node, []):
                new_path = list(path)
                new_path.append(neighbor)
                queue.append(new_path)

print("Path:", bfs('A', 'F'))

Real-World Applications

Navigation Systems

Uses algorithms like A* for finding optimal routes on maps (e.g., Google Maps).

Game Playing

AI in games like Chess or Go uses Minimax and Alpha-Beta pruning for strategic decisions.

Robotics

Path planning for robotic arms or autonomous vehicles uses search for motion planning.

Medical Diagnosis

Search through symptom-disease trees to find the most probable diagnosis.

Web Crawling

Crawlers use BFS/DFS to traverse web pages through links.

Where AI Is Applied

Field Use Case
AI Planning Creating action sequences in smart agents
Computer Vision Pathfinding in grid-based visual data
Natural Language Processing Parsing and sentence generation
Cybersecurity Analyzing paths of intrusion through systems
Logistics Route optimization in delivery systems

Resources

Interview Questions with Answers

What is the difference between informed and uninformed search?

Uninformed search algorithms (like BFS, DFS) don’t use any domain knowledge, while informed search (like A*) uses heuristics to guide the search.

What is a heuristic function?

A heuristic function estimates the cost from a current node to the goal, helping informed search algorithms make better decisions.

How does A* search work?

A* uses both the actual cost from the start node (g) and a heuristic estimate to the goal (h), combined as f(n) = g(n) + h(n).

Which search algorithm guarantees the shortest path?

Breadth-First Search guarantees the shortest path in an unweighted graph.

What is the limitation of DFS?

DFS can get stuck in deep or infinite paths and does not guarantee the shortest solution.